Hi, Cant find this clearly anywhere - at the start of a monsters activation does it get a set amount of movement points to use across its entire go (both actions) or does it get the movement points per action? (I.e. 4 in total or 4 per action (8 total))

If I understand the rules correctly the monster doesn't just get movement points unless it actually has to use a move action. Then it would get its base movement points per movement action activation...if that makes sense.

We've played it as "per action." Move uses up movement points as necessary to accomplish the goal (engage, spot, etc.). Any subsequent action that says "move" or "retreat" gets a new amount of movement points defined by what's on the monster card.

It's the same as if a hero took two movement actions. A hero with three movement points, for example, that chooses to move twice doesn't get just three action points for the whole turn. They get three for the first action and three more for the second action. Same with monsters.